Example Data Table
| Scenario |
Speed |
Angle |
Friction |
Grade |
Transfer Ratio |
Estimated Use |
| Low speed site vehicle |
15 mph |
12° |
0.70 |
0% |
0.60 |
Warehouse yard review |
| Moderate impact |
30 mph |
18° |
0.65 |
2% |
0.72 |
Roadwork access check |
| Higher speed case |
45 mph |
22° |
0.55 |
-1% |
0.80 |
Incident range study |
Formula Used
The calculator combines a launch, airborne travel, and post-landing sliding model.
Impact speed is first converted into meters per second.
Launch speed:
Vlaunch = Vimpact × transfer ratio
Velocity components:
Vx = Vlaunch × cos(angle),
Vy = Vlaunch × sin(angle)
Flight time on graded ground:
0.5gt² - (Vy - Vx tanθ)t - (launch height - landing height) = 0
Airborne distance:
Dair = Vx × t × drag factor
Sliding distance:
Dslide = Ventry² / [2g(μcosθ + sinθ)]
Total throw distance:
Dtotal = contact carry + airborne distance + sliding distance
Air drag is handled with a practical reduction factor based on air density,
drag coefficient, projected area, body mass, and no-drag airborne range.
How to Use This Calculator
- Enter the impact speed and select the correct speed unit.
- Add the speed transfer ratio from your chosen reconstruction assumption.
- Enter launch angle, launch height, grade, and landing height.
- Add sliding friction for the surface condition.
- Include contact carry distance when the person was carried before flight.
- Adjust drag values if air resistance should be included.
- Enter uncertainty to create a low and high distance range.
- Use observed throw distance when you need a reverse speed estimate.
- Click Calculate to show results above the form.
- Use CSV or PDF buttons to export the same calculation.
Pedestrian Throw Distance in Construction Safety
Why Throw Distance Matters
Pedestrian throw distance is used during incident review.
It can support a basic reconstruction of a site impact.
Construction areas often include loaders, trucks, vans, forklifts, and temporary traffic routes.
Each setting has different surface conditions.
A distance estimate helps teams compare scene evidence with possible speed ranges.
It also helps safety officers discuss vehicle controls with clearer numbers.
Key Inputs to Review
Impact speed is the main input.
Small speed changes can produce large distance changes.
Launch angle also matters.
A higher launch angle can increase airborne time.
Surface friction affects the sliding distance after landing.
Dry concrete, wet asphalt, mud, gravel, and steel plates all behave differently.
Grade changes the result too.
Uphill travel reduces slide distance.
Downhill travel can extend it.
Using the Result Wisely
This calculator uses a simplified engineering model.
It is useful for planning, training, and early review.
It should not replace a full forensic investigation.
Real incidents include many details.
Vehicle shape, pedestrian posture, braking, secondary impacts, clothing, and road texture may affect the outcome.
The transfer ratio is especially important.
It represents how much impact speed becomes launch speed.
Users should test several reasonable ratios.
Better Safety Decisions
The result can support better site controls.
Teams can compare throw ranges near gates, crossings, haul roads, and work zones.
They can decide where barriers, spotters, signs, lights, or speed limits are needed.
The exported report is also helpful for meetings.
It keeps assumptions visible.
It lets supervisors review the same numbers.
Clear assumptions make discussions more practical.
They also reduce guesswork during safety planning.
FAQs
1. What is pedestrian throw distance?
It is the distance a pedestrian travels after impact.
It may include contact carry, airborne movement, and sliding after landing.
2. Is this calculator for legal crash reconstruction?
It is an estimating tool.
Legal reconstruction needs scene evidence, validated methods, and qualified expert review.
3. What is the speed transfer ratio?
It estimates how much impact speed becomes pedestrian launch speed.
Users often test several values to compare possible ranges.
4. Why does friction affect the result?
Friction controls sliding after landing.
Lower friction usually increases sliding distance.
Higher friction usually shortens it.
5. What does positive grade mean?
Positive grade means the pedestrian moves uphill.
Uphill motion increases resistance.
Downhill motion may increase the total distance.
6. Should I include air drag?
Air drag is optional.
It has more effect at higher speeds, longer airborne paths, and larger projected areas.
7. What is observed throw distance?
It is the measured distance from impact area to final rest position.
The calculator can reverse-estimate speed from it.
8. Why use an uncertainty percent?
Incident inputs are rarely exact.
Uncertainty creates a low and high range.
This makes the estimate more realistic.